Method of estimating a humidity level in a steam cooking chamber of a steam cooking appliance, method or operating the steam cooking appliance and steam cooking appliance

Abstract

The present application in particular is related to a method of estimating a humidity level in a steam cooking chamber (4) of a steam cooking appliance (1). The method comprises successively measuring static or quasi-static pressure values (P1, . . . , Pn) prevailing within the steam cooking chamber (4); successively calculating from the pressure values (P1, . . . , Pn); and setting and using the humidity index value (EH1, EHn) as an actual measure for the humidity level.

The invention claimed is: 
     
       1. Method of operating a steam cooking process in a steam cooking cavity of a steam cooking appliance comprising:
 a. successively measuring, with a pressure sensor, static or quasi-static pressure values (P 1 , . . . , P n ) prevailing within the steam cooking cavity; 
 b. successively calculating from the pressure values or smoothed pressure values (P 1 , . . . , P n ) via iterative numerical integration a humidity index value (EH 1 , . . . , EH n ), wherein the pressure values (P 1 , . . . , P n ) are measured at successive timepoints (t 1 , . . . , t n ) and an actual humidity index value EH n ) for a pressure value (P n ) is calculated from a preceding humidity index value (EH n−1 ); 
 c. setting and using the humidity index value (EH 1 , . . . , EH n ) as an actual measure for the humidity level; and 
 d. activating or deactivating steam generation in the steam cooking appliance in dependence on the actual measure for the humidity level and at least one preset value of the humidity level. 
 
     
     
       2. Method according to  claim 1 , wherein the pressure sensor, via which the pressure values (P 1 , . . . , P n ) are measured, is arranged outside the cavity and is connected with the inner cavity volume via a communicating pipe. 
     
     
       3. Method according to  claim 1 , wherein the pressure sensor communicates with a zone within the cavity essentially unaffected by forced convection generated in the cavity by a fan. 
     
     
       4. Method according to  claim 1 , wherein the successive humidity index values (EH 1 , . . . , EH n ) are calculated in a weighted iterative numerical integration. 
     
     
       5. Method according to  claim 1 , wherein the humidity index values (EH 1 , . . . , EH n ) are calculated according to the following calculation rule:
     EH   n   =EH   n−1 +( P   n   −P   n−1 )* K   up   −EH   n−1   *K   relax , if  P   n   >P   n−1  or  a.
 
     EH   n   =EH   n−1 +( P   n   −P   n−1 )* K   down   −EH   n−1   *K   relax , if  P   n   ≤P   n−1 ;  b.
 
 wherein EH n  and EH n−1  are successive humidity index values; P n  and P n−1  are successive pressure values or successive smoothed pressure values, K up  is a first weighting factor, K down  is a second weighting factor, and K relax  is a relaxation factor. 
 
     
     
       6. Method according to  claim 5 , wherein the factors K up , K down , and K relax  are calibrated for each application. 
     
     
       7. Method according to  claim 1 , wherein the pressure sensor is adapted to measure pressures in the range from 0 to 30 Pa. 
     
     
       8. Method according to  claim 1 , wherein the pressure sensor is an absolute pressor sensor or a differential pressure sensor which is adapted to measure a difference pressure between inside of the cavity and outside of the cavity. 
     
     
       9. Method according to  claim 1 , wherein the actual humidity index value (EH n ) is further calculated from the pressure value (P n ) and a preceding pressure value (P n−1 ) for the preceding humidity index value (EH n−1 ). 
     
     
       10. Cooking appliance comprising a steam cooking functionality with a steam cooking cavity, a control unit, a pressure sensor and steam generation unit, respectively being coupled to the control unit, wherein the control unit is adapted to operate a steam cooking process according to the method of  claim 1 . 
     
     
       11. Cooking appliance according to  claim 10 , wherein the pressure sensor is mounted outside the cavity, and wherein the pressure sensor is connected to the inner volume of the cavity by a communicating pipe. 
     
     
       12. Cooking appliance according to  claim 11 , comprising a fan for forced ventilation or convection, wherein the communication pipe is connected to a section of the cavity volume which is essentially unaffected by the fan. 
     
     
       13. Cooking appliance according to  claim 10 , wherein the pressure sensor is an absolute pressure sensor or a differential pressure sensor and is adapted to calculate a difference pressure between the inside of the cavity and the outside of the cavity. 
     
     
       14. Cooking appliance according to  claim 10 , wherein the pressure sensor is adapted to sense pressures in the range between 0 and 100 Pa. 
     
     
       15. Cooking appliance according to  claim 10 , wherein the pressure sensor is adapted to sense pressures in the range between 0 Pa and 20 Pa.